A boiler used for heating or warm water is a device configured to heat a desired area or supply warm water by heating water or direct water (hereinafter referred to as a “heating medium”) being heated by a heat source, and the boiler is configured to include a burner configured to combust a mixture of a gas and air and a heat exchanger configured to transfer combustion heat of a combustion gas to the heating medium.
A boiler produced in an early stage uses a heat exchanger which heats a heating medium using only sensible heat generated when a burner performs a combustion operation, but a condensing boiler, which has a sensible heat exchanger configured to absorb sensible heat of a combustion gas generated in a combustion chamber, and a latent heat exchanger configured to absorb latent heat generated by condensation of water vapor contained in the combustion gas which underwent heat exchange in the sensible heat exchanger, is recently being used to improve thermal efficiency. Such a condensing boiler is being applied to an oil boiler as well as a gas boiler, thereby contributing to an increase in boiler efficiency and a reduction in fuel cost.
As described above, a conventional condensing type heat exchanger including a sensible heat exchanger and a latent heat exchanger is configured with a structure in which a blower, a fuel supply nozzle, and a burner are installed above a housing, and the sensible heat exchanger and the latent heat exchanger, which each have a heat exchange fin coupled to an outer side of a heat exchange pipe, are sequentially installed inside the housing below the burner.
However, in the conventional condensing type heat exchanger, there is a problem in that a volume of the heat exchanger is increased due to the blower being disposed above the housing and the structures of the sensible heat exchanger and the latent heat exchanger which are individually installed inside the housing.
As a prior art for improving heat exchange efficiency and minimizing a volume while resolving such a problem, Korean Registered Patent Nos. 10-1321708 and 10-0813807 each disclose a heat exchanger configured with a burner disposed at a central portion of the heat exchanger, and a heat exchange pipe wound around a circumference of the burner in the form of a coil.
In each of the heat exchangers disclosed in the above-described patents, heat generated by combustion in the burner is transferred to an outer side of the combustion chamber and causes overheating of the heat exchanger, and thus heat insulating materials or heat radiating fins are additionally provided on an outer wall of the combustion chamber to prevent the heat transfer and the overheating such that there are problems in that a structure of the heat exchanger becomes complicated and a loss of heat occurs.
Further, the conventional heat exchanger has a structural limitation in that a flow channel of the heating medium is short, and thus a heat transfer area between the heating medium and combustion gas cannot be widely secured.